Friction welding is not a one-size-fits-all process — that’s what makes it such a versatile joining method. It’s just as effective for joining components that you can fit in the palm of your hand as it is for joining parts that require a crane to move from one place to another.
With such multifaceted capabilities, it should come as no surprise that friction welding comes in many forms.
The purpose of this article is to explain which friction welding technology would be most effective for your aerospace application.
Key Advantages Of Friction Welding Technology In The Aerospace Industry
Before we break down each of MTI’s advanced friction welding technologies, let’s talk about some of the advantages of friction welding as a whole.
Friction welding is a more controllable and repeatable process compared to fusion welding. It allows us to control the inputs to achieve consistent metallurgical results.
Another major advantage of friction welding is the ability to utilize bimetallics. This, among many things, leads to cost savings and stronger joints for most aerospace applications.
Additionally, MTI is Nadcap and AS9100-certified. As one of the top aerospace friction welding service providers, we offer friction welding machines that adhere to strict quality and safety standards set by industries surrounding air and space travel.
Now, let’s look at each technology and what it has to offer in the aerospace industry.
Rotary Friction Welding (RFW)
The oldest form of friction welding, Rotary Friction Welding, is a solid-state process in which one part is rotated at high speed while pressed against a stationary part. The resulting friction heats the parts, causing them to forge together with great weld durability.
Rotary Friction Welding is accomplished through either a Direct Drive or Inertia process. In a Direct Drive friction welding machine, the rotating component is accelerated to a desired weld speed using an electric motor.
With Inertia friction welding, the motor spins a flywheel up to speed before disengaging, storing the energy needed for welding as kinetic energy.
In both cases, force is applied between the rotating and stationary components to convert this energy to heat using friction.
MTI has joined many material combinations for the aerospace industry using Rotary friction welding.
Here are some of the most popular applications:
- Fan blade rotors
- Jet engine fan shafts
- Landing gear components
- Compressor discs/ drum assemblies
- Turbine discs/ drum assemblies
- Lightweight pistons for aircraft pumps
- Heat pipes
- Aircraft hook bolts
- Bimetallic aircraft rivets
Rotary friction welding can join a wide range of part geometries, including:
- Tube to tube
- Tube to plate
- Tube to bar
- Tube to disk
- Bar to bar
- Bar to plate
To explore more samples of parts joined through Rotary friction welding, click here.
Linear Friction Welding (LFW)
In Linear Friction Welding, one part moves in a linear motion at high speed and is pressed against another part held stationary. The resulting friction heats the parts, causing them to forge together.
Though the possibilities of Linear friction welding are virtually endless, blisks, wing ribs, and near-net shapes are the applications we join most frequently for the aerospace industry.
For blisks, Linear friction welding is particularly efficient because each blade is welded onto the hub instead of machining the blisk from a single forging. Not only does this reduce material waste, but it also makes repairs much easier.
Linear friction welding is compatible with just about any non-round geometry and is ideal for uniquely shaped geometries.
To view more aerospace parts accomplished through Linear friction welding, click here.
Explore weld development and production possibilities on MTI’s LF35-75, which has the largest tooling envelope of any Linear friction welder in the world.
Find out how Linear friction welding is providing a unique solution for titanium forgings.
Friction Stir Welding (FSW)
Unlike Rotary and Linear friction welding, Friction Stir Welding uses a pin tool to generate the relative motion and force required to make a friction weld along the seam of two stationary parts.
Friction Stir Welding machines are primarily used for joining aluminum sheets, extrusions, and panels. In the aerospace industry, it could also be used for wings, fuel tanks, heat exchangers, and other hermetically sealed enclosures.
This solid-state FSW process is ideal for air and space travel because of its lightweighting capabilities and increased strength in the weld seams.
Many aerospace customers prefer Friction Stir Welding because it supports extensive part lengths and widths — a key benefit for joining oversized components used in aircraft.
Friction Stir Welding can join a wide range of part geometries, including:
- Butt
- Butt Laminate
- Lap
- Butt Both Sides
- T-Butt
If you’re considering using FSW technology for your part prototyping or manufacturing, see our FSW contract welding services to learn more.
Low Force Friction Welding
Low Force Friction Welding is MTI’s newest solid-state joining process. Unlike the methods listed above, Low Force Friction Welding uses an external energy source to raise the interface temperature of the parts being welded. This reduces the process forces required to make a solid-state weld compared to traditional friction welding. The preheat element allows us to create the same quality of joint at a fraction of the force.
Low Force Friction Welding can be achieved with either linear or rotary motion and offers all the advantages of traditional friction welding, but its benefits are maximized.
With Low Force Friction Welding, we can weld the same material combinations and geometries as with traditional friction welding, but the lower process loads allow us to weld items that may not have survived the traditional friction welding process.
With Low Force Friction Welding, we are able to achieve:
- Tighter weld tolerances
- Lower residual stresses
- Improved flash geometry
- Reduction in flash size
- Faster cycle times
- Smaller machine sizes
Of particular interest to aerospace and aviation customers, Low Force Friction Welding allows us to control the amount of upset to match a customer’s request. With different combinations of preheat and relative motion, we can alter the appearance of the flash to benefit a customer’s processing downstream of the friction welder.
MTI is the only organization in the world to have developed, designed, and manufactured Low Force production machines that are operating in industry today.
Click here to find out how Low Force Friction Welding can improve your processes and get started on your development work today.
Plug Welding
Plug Welding is one of the most unique friction welding processes. It’s especially attractive to the aerospace industry because it reduces Maintenance, Repair, and Operations (MRO) expenditures by repairing holes instead of scrapping assemblies due to corrosion or wear.
Plug welding can help restore a hole to near-parent material properties and, subsequently, machine it to its original configuration. This process eliminates the need for airlines to acquire new components or to keep a plane out of service for an extended period.
Choosing The Right Material For Parts In The Aerospace Industry
Now that you understand the friction welding technologies and how each one could benefit the aerospace industry, you may be wondering which material would be best for your project.
Materials joined in applications for air travel are typically high-temperature alloys such as Titanium, Inconel, and powdered nickel alloys.
However, other materials can also be used in low-temperature applications, such as Aluminum alloys, stainless steels, and alloy steels.
No matter which two metals you want to join for your next aerospace project, you can be sure there’s a friction welding process to match it with quality, strength, and repeatability.
At MTI, we offer more than just friction welding machines for contract welding. As one of the leading aerospace friction welding companies, we support aerospace and other mission-critical industries with the rigorous quality standards they require. Our integrated pre- and post-welding services take your project from concept to completion — without the need to rely on outside resources. Explore our Contract Manufacturing services to learn more.